Final answer:
Blood in the hepatic portal vein contains a high concentration of nutrients such as fats and proteins from the digested food and wastes filtered by the spleen, not a high concentration of urea.
Step-by-step explanation:
A sample of blood from the hepatic portal vein is likely to contain a mixture of nutrients absorbed by the gastrointestinal tract because this vein carries blood from the stomach, small intestine, large intestine, and spleen to the liver. In the liver, this blood will contain high concentrations of nutrients, including fats and proteins, that have been absorbed from the digested food, as well as certain wastes filtered out by the spleen. The liver's role includes processing these nutrients and disposing of toxins and other wastes. The hepatic portal vein does not typically carry a high concentration of urea; urea is more commonly found in systemic circulation where it is transported to the kidneys for excretion.